PROJECT SUMMARY/ABSTRACT Endometriosis, a disorder characterized by the presence of endometrial-like tissue outside of the uterus, affects approximately 10% of reproductive age women in the US. Despite its prevalence, the etiology of endometriosis has not been fully delineated. It incurs significant health care costs and greatly impacts quality of life (QOL). Over 80% of women with endometriosis report chronic pelvic pain (CPP) and symptoms are often not sufficiently abated with hormonal suppression or surgery. Hence, the identification of other evidenced- based, modifiable factors, that improve pain and QOL are critical to improving the lives of women with endometriosis. The goal of this study is to evaluate the effects of a 12-week dietary intervention among women with laparoscopically-confirmed endometriosis who had a pain score of at least 7 out of 10 on the Visual Analog Scale (VAS) in the month prior to baseline. The intervention will consist of a diet based on the Alternative Health Eating Index-2010 (AHEI-2010) guidelines, as observational research suggests that adherence to the AHEI-2010 may decrease risk of laparoscopically-diagnosed endometriosis among women experiencing pain symptoms. The specific aims of the proposed study are to test the effect of the AHEI-2010 guideline-based dietary intervention on: 1) the VAS pain score, the pain catastrophizing scale, and mean number of pain pills taken per week; 2) physical and mental QOL components measured with the Endometriosis Health Profile (EHP-30) Questionnaire and Short Form Survey (SF-12); 3) circulating levels of inflammatory markers (IL-6, IL- 1?, hs-CRP, sTNFR-1, sTNFR-2). Women with laparoscopically-confirmed endometriosis (n=100) will be randomized to a 12-week dietary intervention or a control group. The intervention group will have meal ingredients shipped to directly to their home during the first 4 weeks of the intervention. For the remaining 8 weeks, meal plans and recipes will be provided. Pain, quality of life, and inflammatory markers will be assessed at baseline, 4, 8, and 12-weeks using validated questionnaires following the guidelines of the World Endometriosis Research Foundation (WERF) Endometriosis Phenome and Biobanking Harmonization Project (EPHect). In addition, longer-term effects of the intervention will be assessed by examining pain and QOL outcomes at 6 months and 1 year. Many women with endometriosis experience poor QOL due to chronic pelvic pain and other physical and mental sequelae of endometriosis. As symptoms are often not sufficiently abated with hormonal suppression or surgery, the identification of other evidenced-based, modifiable factors, that improve pain and QOL are critical to improving the lives of women with endometriosis.